1. Field of the Disclosure
The present disclosure relates to a liquid crystal display (LCD) device, and particularly, to an LCD device with a light emitting diode (LED) backlight unit capable of providing light to an LCD panel via a plurality of LEDs.
2. Description of the Related Art
Displays provide a medium for providing visual information in an information oriented society, and its importance is further emphasized. In order to occupy a leading position, the display should satisfy requirements, such as low power consumption, thin and light configuration, high image quality and the like.
Displays may be classified into a light emitting type, including a cathode ray tube (CRT), an electroluminescence (EL), a light emitting diode (LED), a vacuum fluorescent display (VED), a field emission display (FED), a plasma display panel (PDP) and the like, and a non-light emitting type which does not emit light by itself, such as a liquid crystal display (LCD).
An LCD device denotes a device for representing an image by using an optical anisotropy characteristic of a liquid crystal. The LCD device can provide a superior visibility to a CRT and implement lower average power consumption than a CRT having the same screen size. Further, it generates a low heating value. Hence, the LCD device is getting spotlighted as a next generation display device, together with the PDP.
Liquid crystal used in the LCD device is not a light emitting material which generates its own light by itself but a photospheric material by which an amount of light coming from the outside is modulated to display an image on a screen. Accordingly, the LCD device requires a separate light source, namely, a backlight unit, for radiating light onto an LCD panel.
Hereinafter, the LCD device will be described in detail.
Even if any specific description is not given, a portion where a lamp is located in an LCD device is referred to as a lower portion, and a portion where an LCD panel is located is referred to as an upper portion.
An LCD device may include an LCD panel having a liquid crystal injected between an array substrate and a color filter substrate for outputting an image, a backlight unit installed at a lower portion of the LCD panel for emitting light all over the LCD panel, and a plurality of casing components for fixedly coupling the LCD panel and the backlight unit to each other.
The backlight unit functions to create plane light with uniform brightness from a lamp used as a light source. Thickness and power consumption of the LCD device may depend on how thin the backlight unit is configured and how efficiently light is useable.
Such backlight units may be divided into an edge type and a direct type according to a position of a light source with respect to a display surface. Further, the light source of the backlight unit may be either a linear light source or a point light source. Here, an example of the linear light source may be a cold cathode fluorescent lamp (CCFL), and an example of the point light source may be a light emitting diode (LED).
The CCFL has often been used as the existing light source of the backlight unit. However, following the recent tendency of an LCD device becoming small, thin and light, it is increased to use an LCD device, which employs a light emitting diode advantageous in view of power consumption, weight, brightness and the like, as a light source of the backlight unit.
Hereinafter, a related art LCD device will be described in detail with reference to the accompanying drawings.
FIG. 1 is a disassembled view showing a schematic configuration of a related art LCD device.
Also, FIG. 2 is a view of a direct type LED backlight unit in the related art LCD device of FIG. 1.
As shown in FIG. 1, a related art LCD device includes an LCD panel 1 for outputting an image, a plurality of LEDs 2 disposed at a lower portion of the LCD panel 1 for emitting light to the LCD panel 1, a diffusion plate 3 disposed between the LCD panel 1 and the LEDs 2 for diffusing light emitted from the LEDs 2, optical sheets 6 for converting light discharged from the diffusion plate 3 to supply to the LCD panel 1, and a bottom cover 7 for covering the LEDs 2.
As shown in FIG. 2, the direct type LED backlight unit employs a method of aligning an LED printed circuit board (PCB) 8, having the LEDs 2 mounted thereon with the bottom cover 7 in a plate type for coupling therebetween.
Here, size and number of the LED PCB 8 depend on a size of the backlight unit and a size capable of employing a surface mounting technology (SMT).
Such fabricated LED PCBs 8 are coupled to the bottom cover 7 by use of screws, holders or the like, together with a reflection sheet (not shown).
In the meantime, the LED backlight unit using the LEDs 2 as light sources further includes the LED PCB 8, as compared to a CRT, thereby causing an increase in fabricating cost.
Further, for coupling the plate type LED PCBs 8 onto the bottom cover 7, the LED PCBs 8 unfortunately use a larger area which is larger than that required for actually installing LEDs and for wiring.
That is, because there is no method provided by which an LED package is mounted and wired directly on the bottom cover, a method has been employed, by which the LED package is first mounted on each LED PCB and then wiring is completed. However, an area of the printed circuit board several times larger than an area used for the LED package and the wiring is used, resulting in consumption of the PCB. That is, a large area of the PCB is used to cover the entire surface of the bottom cover in order to uniformly arrange the LED package all over the backlight unit. Accordingly, a loss of usage area of the LED printed circuit board is caused, and the use efficiency on a mother substrate is also lowered.